1. Field of the Invention
The present invention relates to a cleaning apparatus for a plate-like part which cleans a thin plate-like part such as a semiconductor wafer, a magnetic recording disc medium, a liquid crystal display panel, a Braun tube shadow mask and the like, and a method thereof.
Further, the present invention relates to a fluid treatment method for a substrate and a treating apparatus therefor, and particularly to a fluid treatment method for a substrate which is preferable for fluid treating a plate-like material such as a semiconductor wafer, a liquid crystal substrate, a magnetic disc and the like corresponding to a substrate to be treated in accordance with a single wafer method, and a treating apparatus therefor.
2. Description of the Prior Art
Conventionally, as a structure which cleans the plate-like part such as a silicon wafer and the like, for example, there is known a structure which is disclosed in Japanese Patent Unexamined Publication No. 8-130202 (a first prior art).
The cleaning apparatus described in the first prior art is provided with an upper cleaning plate which is opposed to an upper surface of the wafer, a lower cleaning plate which is opposed to a lower surface of the wafer, and a cylindrical wafer holding device which has an inner diameter coinciding with an outer diameter of the wafer. The wafer is held in a horizontal state, in a state that an outer periphery of the wafer is in contact with an inner peripheral surface of the wafer holding device. The upper cleaning plate and the lower cleaning plate are respectively arranged in parallel to the upper surface and the lower surface of the wafer, and injects a cleaning fluid to the upper surface and the lower surface of the wafer. At this time, the wafer holding device is rotated and the wafer held thereto is also rotated.
The cleaning fluid injected from a center of the upper cleaning plate is flown out from a portion between an outer peripheral edge of the upper cleaning plate and an outer peripheral edge of the upper surface of the wafer through a portion between the upper cleaning plate and the upper surface of the wafer. Further, the cleaning fluid injected from a center of the lower cleaning plate is flown out from a portion between an outer peripheral edge of the lower cleaning plate and an outer peripheral edge of the lower surface of the wafer through a portion between the lower cleaning plate and the lower surface of the wafer. A pressure in accordance with a Bernoulli""s theorem is respectively generated between the upper cleaning plate and the upper surface of the wafer and between the lower cleaning plate and the lower surface of the wafer, by the cleaning fluid which respectively flows therethrough. At a time of rinsing the wafer, a delicate pressure balance is kept between the upper cleaning plate and the upper surface of the wafer and between the lower cleaning plate and the lower surface of the wafer.
However, the first prior art mentioned above takes into consideration a problem that in the case of setting an interval between the upper cleaning plate and the upper surface of the wafer and an interval between the lower cleaning plate and the lower surface of the wafer to an interval which is enough narrow to obtain an effect of improving a cleaning capacity, the wafer and the cleaning plate relatively move in a rinsing and drying step corresponding to the latter half of the wafer rinsing, whereby a static electricity is charged between the both and unnecessary reaction, contamination and damage are generated on the wafer surface.
That is, in the first prior art, since no attention is paid to the generation of the static electricity mentioned above, it is hard to avoid the unnecessary reaction, contamination and damage in the cleaning and drying process. Even in the case that a distance between the cleaning plate and the wafer is increased so as to reduce a flow speed of the fluid and reduce the generated static electricity, thereby reducing a transmission of an ionized ion due to the widened distance so as to reduce a charged amount, it is impossible to achieve a fundamental solution, and it is impossible to expect an effect of improving the cleaning capacity due to employment of the cleaning plate.
On the contrary, in the case of treating the plate-like part by using the narrow space for cleaning and drying, as is executed in the conventional spin cleaning apparatus, there is a method of introducing a gas such as a nitrogen and the like which is charged with positive or negative electricity so as to neutralize the charged electricity, however, this method has a little effect. Because in accordance with the method of employing the charged gas, the gas charging with an opposite polarity to that of the member charging with the static electricity is attracted to the member, thereby neutralizing the charged electricity, however, when introducing the gas charging with the positive or negative electricity to the narrow space, the gas is rapidly mixed with itself and neutralizes itself, so that the effect of neutralizing the charged electricity of the plate-like part corresponding to the subject to be cleaned is rapidly removed. Accordingly, the effect is restrictedly obtained near the pole of the gas supply portion.
Further, as the conventional fluid treating apparatus for the semiconductor substrate and the like in accordance with the single wafer method, there is known a cleaning apparatus which irradiates a treating fluid such as a liquid or a gas toward a substrate while rotating the substrate (for example, Japanese Patent Unexamined Publication No. 4-287922). In the case of performing a cleaning process, a rinsing process and a drying process in this order, the process is performed by subsequently irradiating a cleaning fluid from a first nozzle, a rinsing fluid from a second nozzle and a nitrogen from a third nozzle, toward the substrate while rotating the substrate.
In the case of irradiating the cleaning fluid or the rinsing fluid so as to rotate the substrate, the cleaning fluid or the rinsing fluid is attached to the inner wall of the treating tank. Since the substrate is rotated at a high speed in the drying process, a downward air current toward the substrate is generated together with the rotation and a vortex air current is generated within the treating tank. The cleaning fluid or the rinsing fluid attached to the inner wall of the treating tank is carried on the vortex air current, is attached to the surface of the substrate and causes a recontamination.
As a method of preventing a recontamination to the substrate mentioned above, there is a method of placing a plate opposite to the substrate, for example, there is known a cleaning apparatus disclosed in Japanese Patent Unexamined Publication Nos. 8-130202 and 8-78368. These are structured such that the process is performed by gripping the substrate from upper and lower portions by the cleaning plate and subsequently supplying the cleaning fluid, the rinsing fluid or the nitrogen gas from a center portion, and since it is possible to prevent the air current toward the substrate by the cleaning plate even in the case of high speed rotation, it is possible to prevent the recontamination onto the surface of the substrate.
For example, in a step for restricting a growth of a natural oxidation film such as a step prior to a gate oxidation film forming step of a semiconductor manufacturing step or the like, it is necessary to control an atmosphere after cleaning to a high level for restricting oxidation. In a conventional apparatus having a wide treatment space, since a lot of time is required for replacing the atmosphere, it is necessary to reduce the treatment space as much as possible. Further, it is also possible to reduce an amount of consumption of the treating fluid by making the treatment space small.
However, in the case of performing a drying process by setting an interval between a cleaning plate 7 and a substrate to be treated 8 to 0.6 mm to 1.0 mm with using an apparatus shown in FIG. 17, an inferior drying is partly generated after the drying process. In this case, in FIG. 17, reference numerals 7a and 9a denote a fluid supply port, from which a cleaning fluid necessary for the fluid treatment and a gas for drying and the like are supplied.
As a result of in detail researching a reason for which the inferior drying is generated, it is known that a water drop leaves on the substrate due to the static electricity generated by a rotation of the substrate 8 and the inferior drying is generated due to a reaction between a surface of the substrate and the water drop.
In particular, in the rinsing and drying process after removing the natural oxidation film prior to the gate oxidation film forming process in the semiconductor manufacturing step, or in the rinsing and drying process after removing the natural oxidation film prior to forming a film of a wire material to a bottom portion of a contact hole, an inferior drying so called as a water mark is formed, thereby significantly deteriorating a quality of a product. Further, since the static electricity generated on the surface of the substrate involves the reattachment of foreign materials, a problem is generated.
In the cleaning apparatus for the semiconductor, in order to prevent the recontamination within the apparatus, a fluid contact portion is made of a plastic material which has a high purity and is excellent in a resistance against chemicals, such as a polytetrafluoroethylene, a polyether ether ketone or the like. These plastic material are easily charged, and in particular easily generates the static electricity due to a frictional electricity charge caused by the rotation.
When measuring an electric potential of the static electricity generated on the surface of the cleaning plate after performing the drying process with using the cleaning plate 7 made of a polytetrafluoroethylene, it is known that the electric potential increases in a negative direction toward an outer periphery of the cleaning plate and is reduced in an outermost periphery, as shown in FIG. 18.
Further, when measuring the electric potential of the static electricity on the substrate 2, it is known that a portion at which an absolute value of the electric potential is high exists at substantially the same position as the cleaning plate 7, as shown in FIG. 19.
Further, when measuring the inferior drying, it is known that it is easily generated in the portion where the static electricity is most possibly generated on the substrate 8, as shown in FIG. 20. When switching from the rinsing process to the drying process, the number of rotation is increased (for example, from 100 rpm to 1000 rpm), whereby the rinsing fluid nipped between the surface of the substrate and the cleaning fluid becomes the water drop due to a centrifugal force and is discharged to an outer portion of the substrate. However, it is considered that the static electricity generated by the rotation is generated as shown in FIGS. 18 and 19, and the water drop is attracted to the static electricity so as to leave between the substrate 8 and the cleaning plate 7, thereby causing the inferior drying of the substrate.
The present invention is made so as to solve the problems mentioned above, and an object of the present invention is to provide a cleaning apparatus for a plate-like part which can prevent unnecessary reaction, contamination and damage from being generated on the plate-like part due to a static electricity while maintaining an effect of improving a cleaning capacity due to employment of a cleaning plate, and a method thereof.
Further, an object of the present invention is to solve the conventional problems mentioned above, and to provide a fluid treating method for a substrate which does not generate an inferior drying in a drying process after a fluid treatment such as a cleaning or the like by preventing the static electricity from being generated, and a fluid treating apparatus.
In order to achieve the objects mentioned above, in accordance with the present invention, there is provided a cleaning apparatus for a plate-like part comprising:
supporting and rotating means which supports the plate-like part having two flat surfaces being substantially in parallel to each other and rotates it within the flat surfaces;
a cleaning plate which is placed in the plate-like part rotated by the supporting and rotating means so as to oppose to at least one of the two flat surfaces in a parallel state;
treating fluid injecting means which injects a treating fluid to one flat surface of the plate-like part from the cleaning plate so as to clean one flat surface; and
potential difference applying means which applies a desired potential difference between the plate-like part and the cleaning plate so as to control a terminal end condition (for example, an oxygen terminal condition, that is, an oxidation film condition) after cleaning on one flat surface of the plate-like part.
Further, in accordance with the present invention, there is provided a cleaning apparatus for a plate-like part comprising:
supporting and rotating means which supports the plate-like part having two flat surfaces being substantially in parallel to each other and rotates it within the flat surfaces;
a cleaning plate which is placed in the plate-like part rotated by the supporting and rotating means so as to oppose to at least one of the two flat surfaces in a parallel state;
treating fluid injecting means which injects a treating fluid for cleaning and drying to one flat surface of the plate-like part from the cleaning plate so as to clean one flat surface; and
potential difference applying means which applies a desired potential difference between the plate-like part and the cleaning plate so as to control a terminal end condition (for example, an oxygen terminal condition, that is, an oxidation film condition) after cleaning and drying on one flat surface of the plate-like part.
Further, in accordance with the present invention, there is provided a cleaning apparatus for a plate-like part comprising:
supporting and rotating means which supports the plate-like part having two flat surfaces being substantially in parallel to each other and rotates it within the flat surfaces;
a cleaning plate which is placed in the plate-like part rotated by the supporting and rotating means so as to oppose to at least one of the two flat surfaces in a parallel state;
treating fluid injecting means which injects a treating fluid for cleaning and drying to one flat surface of the plate-like part from the cleaning plate so as to clean one flat surface; and
potential difference applying means which applies a desired negative potential difference to the plate-like part with respect to the cleaning plate so as to control a terminal end condition (for example, an oxygen terminal condition, that is, an oxidation film condition) after cleaning and drying on one flat surface of the plate-like part.
Further, in accordance with the present invention, there is provided a cleaning apparatus for a plate-like part comprising:
supporting and rotating means which supports the plate-like part having two flat surfaces being substantially in parallel to each other and rotates it within the flat surfaces;
a pair of cleaning plates which are placed in the plate-like part rotated by the supporting and rotating means so as to oppose to the two flat surfaces in a parallel state;
treating fluid injecting means which injects a treating fluid to two flat surfaces of the plate-like part from each of the pair of cleaning plates so as to clean two flat surface; and
potential difference applying means which applies a desired potential difference between the plate-like part and the pair of cleaning plates so as to control a terminal end condition (for example, an oxygen terminal condition, that is, an oxidation film condition) after cleaning on two flat surfaces of the plate-like part.
Further, in accordance with the present invention, there is provided a cleaning apparatus for a plate-like part as cited in the above, in which the cleaning plate is constituted by a material having an electric conductivity, and electric power supplying means for supplying electric current to the cleaning plate is provided as the potential difference applying means.
Further, in accordance with the present invention, there is provided a cleaning apparatus for a plate-like part as cited in the above, in which the cleaning plate is constituted by a material having a desired electric charge characteristic, and the potential difference applying means is structured such as to apply a potential difference due to a static electricity charge generated by a relative motion between the cleaning plate and the plate-like part.
Further, in accordance with the present invention, there is provided a cleaning apparatus for a plate-like part as cited in the above, in which the cleaning plate is constituted by a material having an insulative coating applied to at least surface opposing to the plate-like part and having an electric conductivity, and electric power supplying means for supplying electric current to an electrically conductive portion of the cleaning plate is provided as the potential difference applying means.
Further, in accordance with the present invention, there is provided a cleaning apparatus for a plate-like part as cited in the above, in which a supporting member for supporting the plate-like part in the supporting and rotating means is constituted by a material having an electric conductivity, and electric power supplying means for supplying electric current to the supporting member is provided as the potential difference applying means.
Further, in accordance with the present invention, there is provided a cleaning apparatus for a plate-like part as cited in the above, in which both two of the cleaning plates are constituted by a material having an electric conductivity, these cleaning plates are held in an electrically insulated state from the plate-like part and are structured such as to cancel an undesirable electric charge by supplying an electric current to both of them so that a necessary potential difference is applied between the cleaning plate and the plate-like part. In this case, since there is a case that the electrically conductive material is damaged during the cleaning by some chemicals employed for the cleaning fluid, a surface of the cleaning plate is required to be coated with a material having a resistance against chemicals.
Further, in accordance with the present invention, there is provided a cleaning apparatus for a plate-like part as cited in the above, in which the cleaning plate is constituted by a material having a preferable electric charging characteristic, for example, in the case that the plate-like part is a silicone, a polystyrene having an electric charging characteristic similar thereto, whereby a great electric charge over a necessary amount is not generated even when keeping the cleaning plate and the plate-like part in an electrically insulating manner.
Further, in accordance with the present invention, there is provided a cleaning apparatus for a plate-like part as cited in the above, in which in the case that required cleaning levels and chemicals employed for cleaning are different between an upper surface (a front surface) and a lower surface (a back surface) of the plate-like part, two front and back cleaning plates are made of different materials, for example, a fluorocarbon resin, a vinyl chloride or the like, thereby mutually generating an electric charge and changing a characteristic between the front and back of the plate-like part.
Further, in accordance with the present invention, there is provided a cleaning method for a plate-like part comprising the steps of:
injecting a treating fluid from a cleaning plate which is placed in the plate-like part having two flat surfaces being substantially in parallel to each other to one of the flat surfaces of the plate-like part and simultaneously rotating the plate-like part within the flat surface so as to clean one flat surface; and
applying a desired potential difference between the plate-like part and the cleaning plate so as to control a terminal end condition after cleaning on one flat surface of the plate-like part.
Further, in accordance with the present invention, there is provided a cleaning method for a plate-like part comprising the steps of:
injecting a treating fluid from a cleaning plate which is placed in the plate-like part having two flat surfaces being substantially in parallel to each other to one of the flat surfaces of the plate-like part and simultaneously rotating the plate-like part within the flat surface so as to clean one flat surface; and
injecting a drying treating fluid onto one of the flat surfaces of the plate-like part from the cleaning plate, simultaneously rotating the plate-like part within the flat surface so as to dry the one flat surface and simultaneously applying a desired potential difference between the plate-like part and the cleaning plate so as to control a terminal end condition after drying on the one flat surface of the plate-like part.
Further, in accordance with the present invention, there is provided a cleaning method for a plate-like part comprising the steps of:
injecting a treating fluid from a cleaning plate which is placed in the plate-like part having two flat surfaces being substantially in parallel to each other to one of the flat surfaces of the plate-like part and simultaneously rotating the plate-like part within the flat surface so as to clean one flat surface; and
injecting a drying treating fluid onto one of the flat surfaces of the plate-like part from the cleaning plate, simultaneously rotating the plate-like part within the flat surface so as to dry the one flat surface and simultaneously applying a desired negative potential difference to the plate-like part with respect to the cleaning plate so as to control a terminal end condition after cleaning and drying on the one flat surface of the plate-like part.
As mentioned above, in accordance with the structures mentioned above, even when the interval between the cleaning plate and the plate-like part is set to the interval which is enough narrow to obtain the effect of improving the cleaning capacity so as to relatively rotate the plate-like part with respect to the cleaning plate, it is possible to reduce the static electricity charged between the both in the rinsing and drying step corresponding to the latter half step for cleaning the plate-like part so as to prevent the unnecessary reaction, contamination and damage from being generated on the surface of the plate-like part.
Various kinds of reaction, contamination and damage are included in this unnecessary reaction, contamination and damage, however, a generation of an oxidation film, an absorption of foreign matters and a damage of a circuit pattern such as a semiconductor device or the like. The generation of the oxidation film is structured such that an oxygen mixed in the drying process is activated by an electric field caused by the static electricity mentioned above so as to cause an unnecessary oxidation on the surface of the plate-like part such as a wafer or the like. The absorption of the foreign matters is structured such that a member charged by the static electricity attracts fine dusts and absorbs them by an electric force, whereby it is hard to remove them. The damage of the circuit pattern such as the semiconductor device or the like is structured such that since the static electricity charge is unevenly and rapidly discharged in the step of taking the plate-like part such as the wafer or the like out of the apparatus, excessive voltage and current are generated in a part of the already formed circuit pattern such as the semiconductor device or the like, whereby an insulating breakage and damage by a fire are generated.
Further, in order to solve the problems mentioned above, it is important to prevent the static electricity from generating at a time of starting the drying process after the rinsing process is finished. In accordance with the present invention, it is possible to achieve the object by the following first to third methods.
At first, in accordance with a first method, there is provided a fluid treatment method comprising the steps of:
forming a gap corresponding to a fluid passage between both of front and back surfaces of a substrate to be treated and a treating plate provided in such a manner as to oppose to them; and
injecting a fluid from a center portion of the treating plate while relatively rotating the substrate to be treated and the treating plate so as to supply the fluid to the gap corresponding to the fluid passage,
wherein the treating plate is made of an electrically conductive material having a surface natural resistance of 1 Gxcexa9 or less and the step further comprises a step of fluid treating the surface of the substrate to be treated in a state of grounding the treating plate on the earth.
The fluid treatment method can be realized by a fluid treatment apparatus comprising a chuck mechanism for holding a substrate to be treated, a treating plate provided so as to oppose to both front and back surfaces of the substrate to be treated and to form a gap corresponding to a fluid passage on the opposing surfaces, and means for injecting a fluid from a center portion of the treating plate while relatively rotating the substrate to be treated and the treating plate so as to supply the fluid to a gap corresponding to the fluid passage, wherein the treating plate is made of an electrically conductive material having a surface natural resistance of 1 Gxcexa9 or less and the treating plate is grounded on the earth.
Generally, in order to remove the static electricity, it is said to be necessary that the constructing material is set to a non-charging material and the surface natural resistance is set to 1 Gxcexa9 or less. Accordingly, in order to make the treating plate to achieve the effect of preventing an electricity charging, it is necessary to set the natural resistance to 1 Gxcexa9 or less and grounds on the earth.
Since the treating plate mentioned above does not generate the static electricity and the static electricity is not generated on the substrate to be treated corresponding to the plate-like material, an inferior drying is not generated.
In accordance with a second method, there is provided a fluid treatment method comprising the steps of:
forming a gap corresponding to a fluid passage between both of front and back surfaces of a substrate to be treated and a treating plate provided in such a manner as to oppose to them; and
injecting a fluid from a center portion of the treating plate while relatively rotating the substrate to be treated and the treating plate so as to supply the fluid to the gap corresponding to the fluid passage,
wherein at least a surface opposing to the substrate to be treated of the treating plate is coated with an electrically conductive material having a surface natural resistance of 1 Gxcexa9 or less and the step further comprises a step of fluid treating the surface of the substrate to be treated in a state of grounding the coated surface of the treating plate on the earth.
Then, the fluid treatment method can be realized by a fluid treatment apparatus comprising a chuck mechanism for holding a substrate to be treated, a treating plate provided so as to oppose to both front and back surfaces of the substrate to be treated and to form a gap corresponding to a fluid passage on the opposing surfaces, and means for injecting a fluid from a center portion of the treating plate while relatively rotating the substrate to be treated and the treating plate so as to supply the fluid to a gap corresponding to the fluid passage, wherein at least a surface opposing to the substrate to be treated of the treating plate is coated with an electrically conductive material having a natural resistance of 1 Gxcexa9 or less and the coated surface of the treating plate is grounded on the earth.
In this second method, it is also suitable for the case that the treating plate is constituted by an insulating material such as a ceramic, a plastic and the like, or a metal having a high resistance.
Since no static electricity is generated on the treating plate and the substrate to be treated in the same manner as that of the first method, also in the case of coating the surface with the electrically conductive material, it is possible to prevent an inferior drying.
In accordance with a third method, there is provided a fluid treatment method as recited in the first method mentioned above, wherein at least a surface opposing to a substrate to be treated of the treating plate (the electrically conductive material having the natural resistance of 1 Gxcexa9 or less) is constituted by a treating substrate to which a treatment for a resistance against chemicals is applied. Accordingly, various kinds of treating liquid chemicals can be employed as the treating fluid and it is also possible to extend a resisting time of the treating plate. As the chemical resisting process in this case, for example, a diamond coating, and a process of coating an electrically conductive polytetrafluoroethylene, a polyether ether ketone or the like can be applied.
In this case, in each of the methods mentioned above, as the method of relatively rotating the substrate to be treated and the treating plate, for example, there are (1) a method of rotating the substrate to be treated and fixing the treating plate, (2) a method of rotating the treating plate and fixing the substrate to be treated, (3) a method of rotating both of the substrate to be treated and the treating plate (in this case, mutually rotating in opposite directions or differentiating the speeds of rotation in the case of the same rotating directions), and the like.
Any rotating methods can be employed, however, the (1) method is actually excellent since a movable portion is reduced in comparison with the other methods and the construction of the apparatus is simple. In this case, the chuck mechanism for holding the substrate to be treated may also have a rotating function.